Deuterium-labeling Toward Robust Function of Organic Molecules: Enhanced Photo-stability of Partially Deuterated 1', 3', 3'-Trimethyl-6-nitrospiro[2H-1- benzopyran-2, 2'-indoline]

ABSTRACT : eight conformational isomersSynthesis of a deuterium-labeled derivative of nitrospirobenzopyran (NSP), one of representative photochromic compounds, has been described. Four deuteriums were successfully introduced on 1-methyl and α -methyne relative to spiro-carbon in the title compound with more than 95atom%D purity. Main photodegraded products of NSP were two oxindoles in acetonitrile, and additional products were formed in poly(isobutyl-methacrylate) films possibly due to restricted molecular motion in polymer matrix. Quantitative HPLC analysis revealed that partial introduction of deuterium to NSP brought a noticeable isotope effect, recognizable enhancement in photo-resistivity of NSP, i.e., 8.3% in solutions and 29% in polymeric films. Latent durability of synthetic compositions has become a big issue to utilize them in state-of-the-art, optoelectronic devices for stable long-term usage so that technological development toward robustness of molecular based materials is quite important. We focus attention on isotopic derivatization of organic molecules through recently developed catalytic protium(H)-deuterium(D) exchange reactions in D